Question about a Liebig for a 3" Boka

[joeymac]

Perhaps vacuum is pulling the product into the reflux return tube like a syphon. The reflux return tube is longer than the product takeoff tube and has a J-bend to prevent ga from entering the liquid column of the tube as well. If it became full of liquid as can be expected during full reflux column stabilization, perhaps it continues acting like a syphon pulling liquid sideways at he T joint. Not only that, but vapor/gas in the column rushing past a reflux return opening like that, flowing around and away from the opening at the end of the reflux tube, would create a low pressure on the column of the reflux return tube... like a reverse pitot tube. That could be further aiding the behaviour of the liquid to choose the horizontal path.

The only other fluid effect I can think of that might make fluid go down the horizontal path is the coanda effect, but that 90 degree bend is not gradual enough to induce the effect and i also don't think ethanol has the cohesiveness to aid any coanda effect anyways.

So I feel like it's got to be a syphoning/vacuum effect. Try cutting of the last piece of the U bend at the bottom of the reflux return so that the opening on the return tube is facing sideways (perpendicular) to the flow. If it doesn't help at all, you ca n solder a new elbow to the return line... but the more I've thought about, the more I believe centered return is completely overrated anyways

[der wo]

Thanks joey.

Yes, siphon sucking was my first idea too. But sergios return is longer than the take off too. That's why I ask him.
And I don't think anymore this is the problem. Because when the valve is open, you have to add the liebig to the product siphon length. So the "sucking power" should be greater at the product path. At least in theory...

There is a detail at the still, which perhaps is the reason. You cant see it on the video or picture. But before I tell, I want first check up, if there are other ideas and what sergio says. I apologize for this "tactical movement", I hope it leads to more and different answers.

[joeymac]

Thanks joey.

Yes, siphon sucking was my first idea too. But sergios return is longer than the take off too. That's why I ask him.
And I don't think anymore this is the problem. Because when the valve is open, you have to add the liebig to the product siphon length. So the "sucking power" should be greater at the product path. At least in theory...

I agree, but with only a few drops per second exiting the valve and leibig, does it have a chance to fill up and cause a vacuum?

There is a detail at the still, which perhaps is the reason. You cant see it on the video or picture. But before I tell, I want first check up, if there are other ideas and what sergio says. I apologize for this "tactical movement", I hope it leads to more and different answers.

[sergiolis]

Hi der wo and joeymac,
Ummhh ... I only run my 3" squeezer once with a feints run but at the end of the run to collect tails I wide opened the needle-valve and it was working fine. 0% reflux and a huge squirt of product....
But I had a siphon problem in my 2" boka that drove me mad.
But really it has a tiny solution. I Just drilled a 1mm diameter hole in the product tube after the needle-valve and it worked nicely. Besides that if it doesn't work it is so easy to fix it again with solder....

[sergiolis]

I think the cause of the siphon is the long liebig...
Building a super dephlegmator right now

[der wo]

But I had a siphon problem in my 2" boka that drove me mad.
But really it has a tiny solution. I Just drilled a 1mm diameter hole in the product tube after the needle-valve and it worked nicely. Besides that if it doesn't work it is so easy to fix it again with solder....

I also recently drilled such a hole in my liebig. It helped against the surging. The product flow was much more even. But it reduced the maximum wattage. There is a ?ml per second distillate, when it starts, that I get with open valve a bit reflux through the return. And this point is lower with the hole. So I decided to close it again. My system works better with surging than fixed, because it's more safe against unwanted reflux.

[der wo]

joey says, the return is too long.
sergio says, the liebig is too long.
I say, there must be another reason.

But I know one detail more: When the member of the other forum started to build and did water pouring tests with the still head (pouring water into the still head and playing with the valve setting), he noticed surging problems. He fixed it with a little tube inside the reflux return. I told him, it's a stupid idea, but he told me, the water test was very successful, so I believed him. Here a picture of the return and the little pipe, which is placed inside the return:

(He replaced this little brass tube with copper later) Perhaps it simple blocks the product path. But I don't understand, why it worked so well at the water pouring test.

[sergiolis]

That's great der wo. My siphon was clearly worse and the hole saved me... It was a disaster before, losing equilibrium with awful and sudden squirts...

About your friend issue, I would drill the hole because is not a big deal and i would test it.

[der wo]

Directing fluids without having a solution for entering and exiting gases is unpredictable. Either it works or don't. This is the main problem with LM stills.

[sergiolis]

Yes,I'm so sorry, I really cannot help. I can understand my old siphon because the lower slanted plate was fully filled with liquid but in this case with a reflux return I have no idea...

[joeymac]

Directing fluids without having a solution for entering and exiting gases is unpredictable. Either it works or don't. This is the main problem with LM stills.

That's why I like my plain slant plate. The bottom plate overflows and gravity wins... liquid falls down.

[sergiolis]

Joeymac, lol looks like you are against reflux return My siphon problem was with my old 2" rig common slanted plate
Now I have different issues, for instance, right now I need a condenser more powerful... anyway with any system you will face some peculiarities... and many members here are using Reflux Return succesfully...

[sergiolis]

I finished the deplhegmator. In the Bokakob configuration it will be fed with water from the liebig.But I have a question...
I think if I connect the hose at the top of the dephleg (counterflow) water will flow at the bottom and the dephleg will not be full of water.
Should I connect water in at the bottom of the dephleg?

[der wo]

sergiolis,
why don't you ask this in the thread about your shotgun?

Anyway, yes, correct and efficient would be from the liebig to the top of the shotgun. Either you use when starting the water flow pressure to push the air down the shotgun and out the hose (easy with tap water, difficult with a pump) or you need a vent tube at the top of the shotgun to release the air. But I think your shotgun is oversized, so if it is not possible to push the air out, I would try to run it the other way before adding a vent.

[sergiolis]

thanks der wo

[sergiolis]

https://www.youtube.com/watch?v=idVMWef ... e=youtu.be" onclick="window.open(this.href);return false;" rel="nofollow

[der wo]

Looks good.
I think the relatively large diameters of the tubes help, that it works so well. 10mm ID is relatively large.
The packing looks like there is still much room for more wattage.

[sergiolis]

Yesssss der wo!!!!! I'm so happy with your advice about the rflx return!!!!
Imagine that I was running supposedly in my scale at 4200W. Unfortunetly this is the limit capacity of my condenser... But as you know I will try to improve it!
Muchas muchas gracias der wo!!!!!!

[der wo]

In your video the valve was 100% closed? And when you open the valve 100%, do you have some reflux like speedy does?
Here a new video from him: https://www.youtube.com/watch?v=PMw0G1b ... e=youtu.be" onclick="window.open(this.href);return false;" rel="nofollow
First seconds closed valve. Then he opens it 100%, but there is still a bit reflux.

Yes, your condenser... Is a longer spool tube such expensive? This would be the easiest solution...

[sergiolis]

Actually is not so expensive. 26€ for 12" and 33€ for 20". If I install the 20" one I could have 20cm more than now. ummhhhh there are always so many options.... but it's true this is a nice one....
I think the video is meanwhile I was collecting Hearts. Anyway, if I open the valve there is no Reflux. Looks like this 6mm copper piece that speedy put into the return is blocking some liquid and maybe the liquid flows from the plates even with the valve wide open.

[der wo]

...and maybe the liquid flows from the plates even with the valve wide open.

No. It comes out the return. Not visible on the video.
Thanks for the answer. Perhaps we will talk about speedys still in the other thread soon.

[sergiolis]

wow, that is really weird ... then the issue could be located at the needle-valve. I don't know. The rest it's all about gravity and gravity don't fails.